Chapter 19, Problem 51A

Interpretation Introduction

Interpretation:

The source of radiation to which humans are exposed naturally is to be discussed and compared with acceptable level of exposure.

Concept introduction:

The radiations are measured in unit rem.

Answer to Problem 51A

Source of radiations to which human is exposed naturally:

• Cosmic rays
• Earth
• Building material
• Human tissues
• Inhalation of air

The tolerable exposure is 198 rem in a year.

Explanation of Solution

Source of radiations to which human is exposed naturally with its value is:

Source	Exposure (millirems/year)
Cosmic rays	50
Earth	47
Building material	3
Human tissues	21
Inhalation of air	5
Total	126

The dose of radiation which is non-detectable lies in range 0-25 rems

Total exposure comparison= $\frac{25}{126\times {10}^{-3}}$

=198

Conclusion

Source of radiations to which human is exposed naturally are Cosmic rays, Earth, Building material, Human tissues, Inhalation of air. These cause 126 millirems/year exposure to humans.

And the tolerable exposure is 198 rem in a year.